If a thread is open in the "Short Selling Stocks" forum, is it OK to open a new thread in the regular buying stock forums for the same stock? 
The boards are total independent, it is ok to open a topic in the NYSE, NASDAQ and AMEX board and open a topic to the same stock in the Short Selling Stocks board if that stock qualifies to that board.
Also, about the search, if you search for a stock and that stock has open topics in more than one board, you can see the name of the board below the name of the topic, doesn't make any confusion.